It is ridiculous to take away both the serve and volley
Assume his serve was 'only' as good as edberg/mac/rafter, he would have developed into a much better volleyer.. He would probably be closer to edberg/mac on the volleys. Those guys won 6-7 slams. Pete had a better ground game than mac or edberg. I think Pete would still have won 8-10 slams even if his serve was 'only' as good as edberg/mac.